’s KidScape are a disappointment to Micaiah Rich, 5. Just on the other side, Micaiah knows, is the farm and factory exhibit where he likes to build cars and sell them in the play store, said his dad, Brian Rich of Shawnee.

But he can’t go in. That part of the museum has been closed since March 24 as crews work to remove mold that had grown between the interior and exterior walls. The six-week mold abatement project was to have been finishing up right about now.

“We want that farm to open,” Rich said.

The Riches and other families will have to wait a little longer. County officials say the mold problem is much more extensive than they expected. The additional work is now expected to take until June 1 and cost more than twice the $43,000 that was expected.

Mold was discovered about a year ago in walls that are hallways between additions of the building at 6305 Lackman Road in Shawnee. It was thought to be limited to an area that linked the original 1927 stone building to additions built in the 1960s or ’70s.

But once crews got inside to do the work, they found the mold problem extended into two of the galleries as well. That posed a problem, since cabinetry along the walls makes it difficult to get to the mold without gutting the museum, said county facilities manager Joe Waters.

The mold work already has hindered museum operations. Because part of the museum is closed off, the museum now limits KidScape to 49 visitors at a time.

So instead of doing a complete mold abatement on the entire building, the county will spend another $50,000 to remove what they can and add waterproofing to the exterior wall, Waters said.

The county will also have to continue air monitoring at a cost of $15,000 to $25,000 a year, he said. That’s because mold can cause respiratory ailments in some people. The county has monitored the air in the museum for the past year, but the mold count has always been well within safe limits, Waters said.

The plan is “not an ideal solution,” Waters said.

But alternatives would be even more costly and disruptive to the museum. Complete removal of the mold would involve closing or relocating the museum for an extended time and would cost about $150,000 on the approximately 20 percent of the building that is involved, Waters said.

At that rate, “you’re rapidly getting into $400,000, $500,000, $600,000 in a building that it has been our intent to vacate,” he said during a meeting last week with the county commission.

“My concern is that we don’t have any particular reason to believe we won’t have a similar problem elsewhere in the building,” he said.

The condition of the museum presents a problem for the commission. Until last fall, the plan had been to move the museum out of its current digs and into new space at the former King Louie bowling alley at 8788 Metcalf Ave.

But the commission has been divided on whether to keep the King Louie building, which it bought at a discounted price in 2011. In November, the commission voted 4-3 against the issuance of $10.3 million in bonds to remodel the building, leaving the museum move effectively on hold.

Since then, the King Louie building has itself been named one of the area’s most endangered historic buildings by the nonprofit Historic Kansas City.

The stopgap plan will be enough to “keep things in a holding pattern” as long as the air quality monitoring goes well, Waters said. And so far it has. But if that changes, “I can’t say for sure what the answer is then.”

The mold work has caused a dip in attendance at the museum, said Tom McCabe, office manager. Attendance was down about 28 percent this April compared with a year ago — 1,800 visitors compared with 2,500, he said.

That held true on Friday morning, when only the Riches and one other family were in the museum.

Brian and Micaiah are regulars at the museum, since they live only a few blocks away. Brian said it’s difficult to know what the county should do without knowing how extensive the mold is. “I’m always of a mindset that you repair what you have,” he said.

On the other hand, “there’s always that cusp of, do you finally buy a new car or do you keep on repairing it.”